Process for producing butyl acrylate

Abstract

An improved process for producing n-butyl acrylate in high yield and high purity substantially free of acrylic acid, incorporates one or more of the following new process components in an acid-catalyzed esterification process for producing n-butyl acrylate: 1. A hydrolytic recovery component, wherein heavy end adducts produced during the acid-catalyzed esterification are hydrolyzed, recovered, and recycled as valuable reactants from a hydrolytic recovery unit (HRU); 2. A cracking reactor component, preferably used with the HRU, wherein additional valuable reactants are recovered and recycled after treatment in the cracking reactor; and 3. A new distillative component, wherein a crude n-butyl acrylate stream is efficiently distilled in an aqueous mode through an acrylic acid separation column, thereby providing n-butyl acrylate substantially free of acrylic acid and in high yield. The first two components also are applicable to acid-catalyzed processes producing C 1 to C 4 alkyl acrylates. A continuous process producing n-butyl acrylate incorporating all new process components also is disclosed.

We claim: 
     
       1. A method of recovering values selected from at least one of acrylic acid, C 1  -C 4  alkyl acrylates and C 1  -C 4  alkanols from heavy ends produced during production of a C 1  -C 4  alkyl acrylate, comprising the steps of: (A) feeding a stream comprising the heavy ends, water, residual acid catalyst, and optionally a strong acid selected from a mineral acid or sulfonic acid, to a hydrolysis reactor;   (B) distilling an overhead stream containing the values and water from the hydrolysis reactor while maintaining a hydrolysis reactor liquid concentration of from 5 to 40 weight % water and at least 1 weight % acid, the acid comprising the residual acid catalyst and optionally the strong acid;   (C) separating from the distilled overhead stream an organic phase comprising the values and an aqueous phase comprising primarily water, and acrylic acid and the C 1  -C 4  alkanol;   (D) recycling the separated aqueous phase to the hydrolysis reactor;   (E) feeding up to 100% of a bleed stream from the hydrolysis reactor to a cracking reactor;   (F) distilling from the cracking reactor an overhead stream comprising values selected from at least one of acrylic acid, the C 1  -C 4  alkyl acrylate, the C 1  -C 4  alkanol, and water while maintaining a cracking reactor liquid concentration of at least 7.5 weight % acid; and   (G) recovering from the cracking reactor overhead stream at least one of acrylic acid, C 1  -C 4  alkyl acrylate, C 1  -C 4  alkanol and water.   
     
     
       2. The method of claim 1 wherein, the hydrolysis reactor is maintained at 90° to 140° C., 50 to 1000 mm Hg pressure, and the stream has a residence time of 0.5 to 20 hours in the hydrolysis reactor. 
     
     
       3. The method of claim 1 wherein, the cracking reactor is maintained at 90° to 140° C. and a pressure of from 20 to 200 mm Hg, and the bleed stream has a residence time of 0.5 to 20 hours in the cracking reactor. 
     
     
       4. A method of recovering values selected from at least one of acrylic acid, n-butyl acrylate and n-butanol from heavy ends produced during production of n-butyl acrylate, comprising the steps of: (A) feeding a stream comprising the heavy ends, water, residual acid catalyst, and optionally a strong acid selected from a mineral acid or sulfonic acid, to a hydrolysis reactor;   (B) distilling an overhead stream containing the values and water from the hydrolysis reactor while maintaining a hydrolysis reactor liquid concentration of from 5 to 40 weight % water and at least 1 weight % acid, the acid comprising the residual acid catalyst and optionally the strong acid;   (C) separating from the distilled overhead stream an organic phase comprising the values and an aqueous phase comprising primarily water, and acrylic acid and the n-butanol;   (D) recycling the separated aqueous phase to the hydrolysis reactor;   (E) feeding up to 100% of a bleed stream from the hydrolysis reactor to a cracking reactor;   (F) distilling from the cracking reactor an overhead stream comprising values selected from at least one of acrylic acid, n-butyl acrylate, n-butanol, and water while maintaining a cracking reactor liquid concentration of at least 7.5 weight % acid; and   (G) recovering from the cracking reactor overhead stream at least one of acrylic acid, n-butyl acrylate, n-butanol and water.   
     
     
       5. The method of claim 4 wherein, the hydrolysis reactor is maintained at 90° to 140° C., 50 to 1000 mm Hg pressure, and the stream has a residence time of 0.5 to 20 hours in the hydrolysis reactor. 
     
     
       6. The method of claim 4 wherein, the cracking reactor is maintained at 90° to 140° C. and a pressure of from 20 to 200 mm Hg, and the bleed stream has a residence time of 0.5 to 20 hours in the cracking reactor.